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Voltage regulator failed in my Alternator

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Old 04-03-14, 05:36 PM   #1
billydpowe
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Default Voltage regulator failed in my Alternator

my wifes 1999 LS400 is only putting out 11-11.1 volts and autozone says Voltage regulator failed.

OUESTION, has anyone replaced theirs??

is this just a lost cause??

give me your comments...

Oh, none of my warning lights have come on, but my little Cowboy $3. voltage readout says 11-11.1.
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Old 04-03-14, 05:53 PM   #2
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Did autozone actually test it or is that what the parts-monkey behind the counter told you based of the symptoms you came in with?

Very possible it's a voltage regulator, could also be other things. All your cars are high mileage examples so you could have also just worn out the brushes.

You can order the parts to fix the alternator of you can just get a new one. Depends on if you are doing the job yourself or paying someone to do it for you.

Iirc, you can get a good denso (possibly referb) alternator from Rockauto for about $200 without returning the core. The rebuild parts are about $50-75 from Lexus and takes about and hour to do, plus R&R of course. So it's a matter of about a $30-50 difference in the wash...
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Old 04-03-14, 07:28 PM   #3
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Quote:
Originally Posted by Shmee View Post
Did autozone actually test it or is that what the parts-monkey behind the counter told you based of the symptoms you came in with?

Very possible it's a voltage regulator, could also be other things. All your cars are high mileage examples so you could have also just worn out the brushes.

You can order the parts to fix the alternator of you can just get a new one. Depends on if you are doing the job yourself or paying someone to do it for you.

Iirc, you can get a good denso (possibly referb) alternator from Rockauto for about $200 without returning the core. The rebuild parts are about $50-75 from Lexus and takes about and hour to do, plus R&R of course. So it's a matter of about a $30-50 difference in the wash...
On that note, I am in the market for rebuilding my alternator myself. Is there anyway you could list the parts necessary for the rebuild?

Brush, Voltage regulator, .... but what else? Is there anything else you need to change out to?
This can help OP also!
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Old 04-03-14, 08:19 PM   #4
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actually, the voltage regulator is very reliable on the factory alternator, and usually when a regulator fails, the voltage will be too high, rather than too low

some aftermarket alternators do skimp on the size of the heat sink for the voltage regulator though, so if your alternator is original, I would get the replacement at advance auto parts, because they have a very small core charge of only about $20, allowing you to keep the outstanding Nippon Denso alternator and its awesome regulator and heatsink to be repaired later.

also, if you don't fix the power steering leak, the replacement alternator will soon go bad for the same reason this one did! (power steering fluid leaking into it)

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Old 04-03-14, 08:30 PM   #5
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Quote:
Originally Posted by billydpowe View Post
my wifes 1999 LS400 is only putting out 11-11.1 volts and autozone says Voltage regulator failed.

OUESTION, has anyone replaced theirs??

is this just a lost cause??

give me your comments...

Oh, none of my warning lights have come on, but my little Cowboy $3. voltage readout says 11-11.1.
Judging from 2 conditions, the voltage too low and no charge warning light, I assume the connector or the cable attached to the alternator or the other side of it is not fully OK. Sometimes the problem might be at in between them though. I have never seen a failed Denso regulator and you'd better to check connections first.

Speaking of failed alternators, I often see worn slip rings among them that got the leaking power steering oil and it turns the charge warning light on. The charge warning light is enabled on by the circuit in the regulator when the generating voltage is below the threshold. Since yours is not on and it sounds like a failed regulator but you'd better to check connections first. Is the connector fully inserted or aren't there any bad connections?
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Old 04-03-14, 09:28 PM   #6
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when my original Nippon Denso alternator failed due to power steering leakage, I also had low voltage and no warning light!
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Old 04-03-14, 09:53 PM   #7
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Not sure where you are in tx but there is a great place in Richardson that rebuilds starters and alternators should you decide you need that.
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Old 04-04-14, 11:55 AM   #8
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Quote:
Originally Posted by LScowboyLS View Post
also, if you don't fix the power steering leak, the replacement alternator will soon go bad for the same reason this one did! (power steering fluid leaking into it)
I have no power steering leak.
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Old 04-04-14, 12:09 PM   #9
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what is the mileage? - Nippon Denso original alternator should go 250K with no PS leak, and even then it just needs a light rebuild.

PS - in case it is not obvious to some of the newer DIY guys here, the voltage regulator is built into the alternator itself, not sure if any of us made that clear.

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Old 04-04-14, 04:06 PM   #10
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Quote:
Originally Posted by LScowboyLS View Post
what is the mileage? - Nippon Denso original alternator should go 250K with no PS leak, and even then it just needs a light rebuild.

PS - in case it is not obvious to some of the newer DIY guys here, the voltage regulator is built into the alternator itself, not sure if any of us made that clear.
hers is at 187k, I ordered a Denso rebuilt without core so I could rebuild it, cause mine is 238+
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Old 04-04-14, 04:09 PM   #11
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Default Altornator

I took the alternator out when I recently rebuilt PS pump. The alternator was covered with oil scums so I decided to take the alternator apart to clean. Hard part was to take the pulley out without a impact wrench. I took the alternator to a local part store and they took the pulley out. Then afterward, put the pulley back on. Two trips.

Only thing they replace when you take an alternator for rebuild are, bearing, regulator/rectifier & brush. May be I should have took some pictures to post.... but it was pretty straight forward. Brushes are same for my old Camry and still had 30% life remaining but I replaced it with new one. Replacing brush for Denso does not require to take the alternator apart. Just open the back panel and pop out the brush and pop it back in.

If you are in doubt, why not get a second opinion from second source. I think an alternator specialist would be a good place to get a second opinion.

Rectifier is an important part. Without a rectifier, if the voltage is high, you could fry important electronics circuit boards.
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Old 04-10-14, 12:29 PM   #12
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WELL my nephew replaced my alternator with a rebuilt one, and guess what, still not charging... took it to Richardson Generator and they said, YEP, not charging... and said probably the wiring plug (3 prong) on the back of the Alt, was bad.. said they are very hard to get off and it is probably broken... they ordered one, said next tuesday or wednesday they would have it.. had them recheck the old alternator, and it checked out OK, no problem... my question is, I have owned this car for over 4 years, if that plug is bad, how did it get that way?

looking for answers??

here is my takeoff...
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Old 04-10-14, 01:32 PM   #13
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age, heat, and chemical deterioration are the main reasons for connectors and wiring to fail assuming no ham-fisted hack was ever working on or was rough with it.
If it gets to the point of the sheathing breaking down or the connector becoming brittle, moisture can get in and corrode things. But you live in Tx and that stuff is more an issue with Northern climates that see harsh winters or tons of rain... you likely do not see the wild temp fluctuations needed for that to happen.

it's hard to be sure without pictures.
My guess is the previous owner/ guy in there last probably damaged it some how and it's taken the 4+ years to become a real problem?
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Old 04-10-14, 04:38 PM   #14
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Quote:
Originally Posted by billydpowe View Post
WELL my nephew replaced my alternator with a rebuilt one, and guess what, still not charging... took it to Richardson Generator and they said, YEP, not charging... and said probably the wiring plug (3 prong) on the back of the Alt, was bad.. said they are very hard to get off and it is probably broken... they ordered one, said next tuesday or wednesday they would have it.. had them recheck the old alternator, and it checked out OK, no problem... my question is, I have owned this car for over 4 years, if that plug is bad, how did it get that way?

looking for answers??

here is my takeoff...
That three prong wiring plug is hard to unplug. I had to drop down the alternator on my garage floor to take back panels off to get that unplugged. Not sure the function of the plug.
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Old 04-10-14, 05:17 PM   #15
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Not sure. But I would have sent you to Richardson Generator also...good guys there.
Glad you found the problem.
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